Many indicators suggest that the influenza A (H5N1) virus is closer to extending beyond Southeast Asia and into the worldwide population, write Priya Sampathkumar, M.D., Mayo Clinic Division of Infectious Diseases, and Dennis Maki, M.D., University of Wisconsin Medical School's Section of Infectious Diseases. They co-authored an editorial in the current issue of Mayo Clinic Proceedings.
The bird flu outbreak in Asia is caused by the "H5N1 virus," an influenza A virus subtype producing serious disease in domestic poultry. The co-authors note that recent genetic research on the influenza A virus responsible for the largest documented influenza pandemic on record -- the Great Influenza Epidemic of 1918 (the "Spanish Flu") -- shows that this virus was entirely of avian origin. The 1918 pandemic was the first confirmed bird flu outbreak in humans. Drs. Sampathkumar and Maki emphasize though that major genetic alterations in the current H5N1 virus must occur before rapid human-to-human spread, essential for a pandemic, is likely.
"If an avian flu pandemic were to occur this winter, we would not be adequately prepared to deal with it," says Dr. Sampathkumar. However, the co-authors say that quarantining methods, antiviral medications and other measures could help contain an outbreak at its earliest stages, if health professionals can ensure the following:
- Very early identification of cases and efficient ongoing surveillance for new cases.
- Sufficient stockpiles of antivirals, with the capacity for rapid delivery of antivirals to the target groups.
- Rapid institution and enforcement of quarantine measures and a high level of compliance with these measures among the target population.
- International cooperation with the strategies above, including travel restrictions and, perhaps most importantly, sharing of national antiviral stockpiles.
The co-authors say that even if these strategies don't curtail a pandemic, they might buy the world precious time to better prepare by ramping up production of vaccine and antivirals, both of which could save millions of lives.
These suggestions to practicing physicians may help in answering patients' questions:
- Will getting a flu shot protect me from avian influenza? The annual flu shot does not protect against the new avian flu strain that originated in Asia. But getting the flu shot is a good idea to protect against seasonal influenza.
- What can I do to protect myself against influenza -- especially if I travel frequently? Travelers to countries where avian influenza is endemic in bird populations should avoid contact with poultry or with surfaces that may have been contaminated by poultry or their feces or secretions. Eating poultry products is safe so long as they are fully cooked. Practice frequent hand washing.
- Do antivirals work? Should I have my own supply of antivirals? The antiviral drugs -- oseltamivir (Tamiflu) and zanamivir (Relenza) -- have shown good activity against most H5N1 strains. However, giving prescriptions for these drugs to individual patients in advance of a pandemic may divert the limited supplies of these medications from people who need them. Many health care centers, including Mayo Clinic in Rochester, Minn., have pre-emptively restricted prescribing oseltamivir, limiting it to patients with clear indications for treatment of probable influenza or its prevention.
For the latest updates on avian influenza, see the following Web sites:
- Centers for Disease Control and Prevention: www.cdc.gov/flu/avian
- Centers for Disease Control and Prevention Travelers' Health: www.cdc.gov/travel
- World Health Organization: www.who.int/csr/disease/avian_influenza
- New Scientist Bird Flu: www.newscientist.com/channel/health/bird-flu
A peer-review journal, Mayo Clinic Proceedings publishes original articles and reviews dealing with clinical and laboratory medicine, clinical research, basic science research and clinical epidemiology. Mayo Clinic Proceedings is published monthly by Mayo Foundation for Medical Education and Research as part of its commitment to the medical education of physicians. The journal has been published for more than 75 years and has a circulation of 130,000 nationally and internationally. Articles are available online at www.mayoclinicproceedings.com.